scholarly journals Mechanical and Crack-Sensing Capabilities of Mode-I Joints with Carbon-Nanotube-Reinforced Adhesive Films under Hydrothermal Aging Conditions

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2290
Author(s):  
Xoan F. Sánchez-Romate ◽  
Jesús Martin ◽  
María Sánchez ◽  
Alejandro Ureña
Keyword(s):  
Carbon Nanotube ◽  
Crack Propagation ◽  
Electrical Resistance ◽  
Crack Detection ◽  
Electrical Response ◽  
Mode I ◽  
Hydrothermal Aging ◽  
Unstable Crack ◽  
Plasticization Effect ◽  
Aging Conditions

The fracture behavior and crack sensing of mode-I joints with carbon nanotube (CNT)-reinforced adhesive films were explored in this paper under hydrothermal aging conditions. The measured fracture energy of CNT-reinforced joints in grit blasting conditions is higher for non-aged samples than for neat adhesive joints (around 20%) due to the nanofiller toughening and crack bridging effects. However, in the case of brushed surface-treated adherents, a drastic decrease is observed with the addition of CNTs (around 70%) due to the enhanced tribological properties of the nanofillers. Hydrothermal aging has a greater effect in the CNT-reinforced samples, showing a more prevalent plasticization effect, which is confirmed by the R-curves of the specimens. The effects of surface treatment on the crack propagation properties was observed by electrical resistance monitoring, where brushed samples showed a more unstable electrical response, explained by more unstable crack propagation and reflected by sharp increases of the electrical resistance. Aged specimens showed a very uniform increase of electrical resistance due to slower crack propagation, as induced by the plasticization effect of water. Therefore, the proposed adhesive shows a high applicability for crack detection and propagation without decreasing the mechanical properties.

scholarly journals Electrical Monitoring as a Novel Route to Understanding the Aging Mechanisms of Carbon Nanotube-Doped Adhesive Film Joints

2020 ◽  
Vol 10 (7) ◽  
pp. 2566 ◽  
Author(s):  
Xoan F. Sánchez-Romate ◽  
Alberto Jiménez-Suárez ◽  
María Sánchez ◽  
Silvia G. Prolongo ◽  
Alfredo Güemes ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Theoretical Calculations ◽  
Electrical Response ◽  
Partial Recovery ◽  
Initial State ◽  
Scanning Calorimetry ◽  
Resistance Change ◽  
Adhesive Film ◽  
Lap Shear ◽  
Aging Conditions

Carbon fiber-reinforced plastic bonded joints with novel carbon nanotube (CNT) adhesive films were manufactured and tested under different aging conditions by varying the surfactant content added to enhance CNT dispersion. Single lap shear (SLS) tests were conducted in their initial state and after 1 and 2 months immersed in distilled water at 60 °C. In addition, their electrical response was measured in terms of the electrical resistance change through thickness. The lap shear strength showed an initial decrease due to plasticization of weak hydrogen bonds, and then a partial recovery due to secondary crosslinking. This plasticization effect was confirmed by differential scanning calorimetry analysis with a decrease in the glass transition temperature. The electrical response varied with aging conditions, showing a higher plasticity region in the 1-month SLS joints, and a sharper increase in the case of the non-aged and 2-month-aged samples; these changes were more prevalent with increasing surfactant content. By adjusting the measured electrical data to simple theoretical calculations, it was possible to establish the first estimation of damage accumulation, which was higher in the case of non-aged and 2-month-aged samples, due to the presence of more prevalent brittle mechanisms for the CNT-doped joints.

EFFECT OF CURING TEMPERATURE OF EPOXY RESIN ON THE ELECTRICAL RESPONSE OF CARBON NANOTUBE YARN MONOFILAMENT COMPOSITES

2021 ◽  
Author(s):  
OMAR RODRIGUEZ-UICAB ◽  
JANDRO L. ABOT ◽  
FRANCIS AVILÉS
Keyword(s):  
Carbon Nanotube ◽  
Epoxy Resin ◽  
Electrical Resistance ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Negative Temperature Coefficient ◽  
Electrical Response ◽  
Negative Temperature ◽  
Curing Temperature ◽  
Temperature Coefficient Of Resistance

The cyclic thermoresistive response of individual carbon nanotube yarns (CNTYs) embedded into epoxy resins is investigated. The influence of the temperature at which the epoxy resin cures on the thermoresistive response is investigated by using two epoxy resins, one that cures at room temperature and the other one that cures at 130 °C. Heating-cooling cycles ranging from room temperature (RT, 25 °C) to 80 °C, incremental cycles (RT to 40 °C, RT to 60 °C and RT to 80 °C) and incremental heating-dwell cycles are applied to monofilament composites, while their electrical resistance is simultaneously recorded. The monofilament composites showed a negative temperature coefficient of resistance during the heating-cooling cycles of -7.07x10-4 °C-1 for specimens cured at high temperature, and -5.93x10-4 °C-1 for specimens cured at room temperature. The hysteresis after the different heating-cooling cycles was slightly smaller for specimens cured at 130 °C, in comparison to specimens cured at room temperature. Several factors including the intrinsic thermoresistivity of CNTY, level of infiltration and the effect of curing temperature may explain the thermoresistive sensitivity of the monofilament composites.

CYCLIC THERMORESISTIVITY OF CARBON NANOTUBE YARN/SILICONE RUBBER MATRIX MONOFILAMENT COMPOSITES

2021 ◽  
Author(s):  
TANNAZ TAYYARIAN ◽  
OMAR RODRIGUEZ-UICAB ◽  
TANJEE AFREEN ◽  
JANDRO L. ABOT
Keyword(s):  
Carbon Nanotube ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Electrical Response ◽  
Negative Temperature ◽  
Curing Kinetics ◽  
Rubber Matrix ◽  
Continuous Heating ◽  
Average Value ◽  
Heating And Cooling

Thermoresistive characterization of CNTY monofilament composites was investigated by using the electrical response of a single carbon nanotube yarn (CNTY) embedded in a silicone polymer forming monofilament composites. Two room temperature vulcanizing (RTV) silicone rubbers with different polymerization mechanisms (OOMOO and Ecoflex) were used as the polymeric matrices. Continuous heating-cooling thermal cycling ranging from room temperature (RT~25 °C) to 80 °C was performed in order to determine the thermoresistive sensitivity, hysteresis and residual fractional change in electrical resistance after each cycle. The thermoresistive response was nearly linear, with negative temperature coefficient of resistance at the heating and cooling zones for CNTY/ OOMOO and CNTY/Ecoflex specimens. The average value of this coefficient at the heating and cooling sections was - 6.65×10-4 °C-1 for CNTY/OOMOO and -7.35×10-4 °C-1 for CNTY/Ecoflex. Both monofilament composites showed a negligible negative residual electrical resistance with an average value of ~ -0.08% for CNTY/OOMOO and ~ -0.20% for CNTY/Ecoflex after each cycle. The hysteresis yielded ~19.3% for CNTY/OOMOO and ~29.2% in CNTY/Ecoflex after each cycle. Therefore, the curing kinetics and viscosity play a paramount role in the electrical response of the CNTY immersed into these rubbery matrices.

scholarly journals Experimental characterization of the quasi-static and dynamic piezoresistive behavior of multi-walled carbon nanotubes/elastomer composites

2020 ◽  
Vol 39 (7-8) ◽  
pp. 299-310 ◽  
Author(s):  
Nicolas Penvern ◽  
André Langlet ◽  
Michel Gratton ◽  
Marcel Mansion ◽  
Nourredine Aït Hocine
Keyword(s):  
Carbon Nanotube ◽  
Electrical Resistance ◽  
Electrical Response ◽  
Dynamic Compression ◽  
Pressure Sensors ◽  
Weight Fraction ◽  
Major Influence ◽  
Static Compression ◽  
Multi Walled Carbon Nanotube ◽  
Elastomer Composites

Multi-walled carbon nanotube (MWCNT)/elastomer composites exhibit a piezoresistive behavior, i.e. their resistivity changes when they are subjected to mechanical loading. Thus, these materials can be used as strain or pressure sensors. In this paper, the effect of carbon nanotube weight fraction on the sensitivity and repeatability of the electrical response of multi-walled carbon nanotube/ethylene–propylene–diene monomer composites is investigated, under quasi-static and dynamic compression (using split Hopkinson pressure bars). It was found that multi-walled carbon nanotube weight fraction and the strain rate have a major influence on the piezoresistivity of such composites. Although all samples exhibited a good repeatability of their electrical response under quasi-static cyclic compression, those with a lower multi-walled carbon nanotube weight fraction had a higher sensitivity to strain. An increase in the electrical resistance during compression was observed under both quasi-static and dynamic compression. Reversible movements of multi-walled carbon nanotube in the transverse direction of compression increased the average inter-multi-walled carbon nanotube distance under quasi-static compression, leading to higher values of resistance. After the dynamic tests, the Young’s modulus of the composites decreased by about 45% and the electrical resistance increased a hundredfold, indicating damage induced by dynamic loading.

scholarly journals Electrical Resistance Sensing of Epoxy Curing Using an Embedded Carbon Nanotube Yarn

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3230 ◽  
Author(s):  
Omar Rodríguez-Uicab ◽  
Jandro L. Abot ◽  
Francis Avilés
Keyword(s):  
Carbon Nanotube ◽  
Epoxy Resin ◽  
Electrical Resistance ◽  
Electrical Response ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Polymerization Process ◽  
Curing Agent ◽  
Resin Curing ◽  
Over Time

Curing effects were investigated by using the electrical response of a single carbon nanotube yarn (CNTY) embedded in an epoxy resin during the polymerization process. Two epoxy resins of different viscosities and curing temperatures were investigated, varying also the concentration of the curing agent. It is shown that the kinetics of resin curing can be followed by using the electrical response of an individual CNTY embedded in the resin. The electrical resistance of an embedded CNTY increased (~9%) after resin curing for an epoxy resin cured at 130 °C with viscosity of ~59 cP at the pouring/curing temperature (“Epon 862”), while it decreased (~ −9%) for a different epoxy cured at 60 °C, whose viscosity is about double at the corresponding curing temperature. Lowering the curing temperature from 60 °C to room temperature caused slower and smoother changes of electrical resistance over time and smaller (positive) residual resistance. Increasing the concentration of the curing agent caused a faster curing kinetics and, consequently, more abrupt changes of electrical resistance over time, with negative residual electrical resistance. Therefore, the resin viscosity and curing kinetics play a paramount role in the CNTY wicking, wetting and resin infiltration processes, which ultimately govern the electrical response of the CNTY immersed into epoxy.

scholarly journals Crack and Electrical Resistance Behaviors of Carbon Nanotube-Based Polymer Composites under Mixed-Mode I/II Loading

2013 ◽  
Vol 54 (7) ◽  
pp. 1105-1109 ◽  
Author(s):  
Tomo Takeda ◽  
Yasuhide Shindo ◽  
Fumitsugu Naraoka ◽  
Yu Kuronuma ◽  
Fumio Narita
Keyword(s):  
Carbon Nanotube ◽  
Polymer Composites ◽  
Electrical Resistance ◽  
Mixed Mode ◽  
Mode I

scholarly journals Effect of Polymer Viscosity and Polymerization Kinetics on the Electrical Response of Carbon Nanotube Yarn/Vinyl Ester Monofilament Composites

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 783
Author(s):  
Omar Rodríguez-Uicab ◽  
Ian Guay ◽  
Jandro L. Abot ◽  
Francis Avilés
Keyword(s):  
Carbon Nanotube ◽  
Electrical Resistance ◽  
Vinyl Ester ◽  
Electrical Response ◽  
Monomer Concentration ◽  
Polymerization Kinetics ◽  
Vinyl Ester Resin ◽  
Styrene Monomer ◽  
Reduced Viscosity ◽  
Initial Decrease

The effect of polymerization kinetics and resin viscosity on the electrical response of a single carbon nanotube yarn (CNTY) embedded in a vinyl ester resin (VER) during polymerization was investigated. To analyze the effect of the polymerization kinetics, the concentration of initiator (methyl ethyl ketone peroxide) was varied at three levels, 0.6, 0.9, and 1.2 wt.%. Styrene monomer was added to VER, to reduce the polymer viscosity and to determine its effect on the electrical response of the CNTY upon resin wetting and infiltration. Upon wetting and wicking of the CNTY by VER, a transient decrease in the CNTY electrical resistance (ca. −8%) was observed for all initiator concentrations. For longer times, this initial decrease in electrical resistance may become a monotonic decrease (up to ca. −17%) or change its trend, depending on the initiator concentration. A higher concentration of initiator showed faster and more negative electrical resistance changes, which correlate with faster gel times and higher build-up of residual stresses. An increase in styrene monomer concentration (reduced viscosity) resulted in an upward shift of the electrical resistance to less negative values. Several mechanisms, including wetting, wicking, infiltration, electronic transfer, and shrinkage, are attributed to the complex electrical response of the CNTY upon resin wetting and infiltration.

scholarly journals Monitoring of Curing and Cyclic Thermoresistive Response Using Monofilament Carbon Nanotube Yarn Silicone Composites

2021 ◽  
Vol 7 (3) ◽  
pp. 60
Author(s):  
Tannaz Tayyarian ◽  
Omar Rodríguez-Uicab ◽  
Jandro L. Abot
Keyword(s):  
Carbon Nanotube ◽  
Heating Rate ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Electrical Response ◽  
Negative Temperature ◽  
Curing Kinetics ◽  
Curing Process ◽  
Resistance Change ◽  
Electrical Resistance Change

The curing process and thermoresistive response of a single carbon nanotube yarn (CNTY) embedded in a room temperature vulcanizing (RTV) silicone forming a CNTY monofilament composite were investigated toward potential applications in integrated curing monitoring and temperature sensing. Two RTV silicones of different crosslinking mechanisms, SR1 and SR2 (tin- and platinum-cured, respectively), were used to investigate their curing kinetics using the electrical response of the CNTY. It is shown that the relative electrical resistance change of CNTY/SR1 and CNTY/SR2 monofilament composites increased by 3.8% and 3.3%, respectively, after completion of the curing process. The thermoresistive characterization of the CNTY monofilament composites was conducted during heating–cooling ramps ranging from room temperature (RT~25 °C) to 100 °C. The thermoresistive response was nearly linear with a negative temperature coefficient of resistance (TCR) at heating and cooling sections for both CNTY/SR1 and CNTY/SR2 monofilament composites. The average TCR value was −8.36 × 10−4 °C−1 for CNTY/SR1 and −7.26 × 10−4 °C−1 for CNTY/SR2. Both monofilament composites showed a negligible negative residual relative electrical resistance change with average values of ~−0.11% for CNTY/SR1 and ~−0.16% for CNTY/SR2 after each cycle. The hysteresis amounted to ~21.85% in CNTY/SR1 and ~29.80% in CNTY/SR2 after each cycle. In addition, the effect of heating rate on the thermoresistive sensitivity of CNTY monofilament composites was investigated and it was shown that it reduces as the heating rate increases.

Mechanism of irregular crack-propagation in thermal controlled fracture of ceramics induced by microwave

2020 ◽  
Vol 21 (6) ◽  
pp. 610
Author(s):  
Xiaoliang Cheng ◽  
Chunyang Zhao ◽  
Hailong Wang ◽  
Yang Wang ◽  
Zhenlong Wang
Keyword(s):  
Crack Propagation ◽  
Industrial Application ◽  
Ceramic Materials ◽  
Advanced Technology ◽  
Analytical Models ◽  
Propagation Mechanism ◽  
Unstable Crack ◽  
Fracture Simulation ◽  
Initial Stage ◽  
Controlled Fracture

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

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